Sleep, nutrition and recovery in athletes

Doherty, Rónán (2021) Sleep, nutrition and recovery in athletes. Doctoral thesis, Northumbria University.

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Abstract

Elite athletes are vulnerable to sleep difficulties due to high training and competition loads, while inadequate sleep has a detrimental impact on both cognitive performance (i.e. alertness, reaction time, memory and decision making) and physical performance as well as injury risk being increased. Adequate sleep can counteract the negative performance, cognitive, immunity, oxidative stress (OS), non-functional overreaching (NFO) and increased pain outcomes that are consequences of sleep debt. Reduced sleep is associated with increased catabolic and reduced anabolic hormones which results in impaired muscle protein synthesis, blunting training adaptations and recovery which may lead to compromised performance. The aim of Chapters 1-3 was to scope the literature to determine a) was there a problem with sleep in athletes, b) is it related to recovery and c) what non-pharmacological options were there to manage both. The research demonstrated a problem with sleep in athletes and a relationship with recovery, it also became clear that Chrononutrition is an area that shows promise, therefore it was necessary to characterise sleep in athletes (Chapter 4), and under specific circumstances (Competition travel – Chapter 5). This allowed the indetification of the specific sleep amd recovery areas of concern in this population with a view to implementing a chrononutritional intervention (Kiwifruit – Chapter 6) to ascertain whether it improved sleep and recovery in general, and specifically in those domains that were most affected in the first two studies.

An investigation of the sleep and recovery practices of athletes, outlined in Chapter 4, demonstrated that 64% of athletes were classified as ‘poor sleepers’, while 21% reported excessive daytime sleepiness. Total sleep time (TST) was lower in the elite athlete group on both training/competition days and rest days, adding to the evidence that elite athletes are particularly vulnerable to sleep difficulties. Significantly, higher levels of sport-specific recovery were observed in the elite athlete group. Pain was reported by 50% of athletes while anxiety/depression was reported by 34% of athletes. In terms of nutrition, the most consumed supplements were whey protein, caffeine, multivitamins, creatine, fish oil, probiotics and vitamin D, while sub-elite athletes reported drinking more alcohol that the elite athletes.

The results of Chapter 5 indicated the following impact of long-haul eastward travel across 7 time zones on sleep: actigraphy derived time in bed, total sleep time and sleep efficiency, and sleep diary derived time in bed, total sleep time, fatigue going to bed and sleep quality. Each were significantly negatively impacted by long haul travel particulalry on the travel day and the following day i.e. the 48 hours post travel.

Chapter 6 highlighted the positive impact of Kiwifruit consumption (2 kiwifruit 1 hour before bed) on key aspects of sleep and recovery in elite athletes. From baseline to post-intervention there were clinically significant improvements in sleep quality (i.e. improved PSQI global scores and sleep quality component scores) and improvements in recovery stress balance (reduced general stress and sports stress scales). Moreover, the intervention improved sleep as evidenced by significant increases in TST and sleep efficiency % and significant reductions in number of awakenings and wake after sleep onset. The findings broadly suggested that Kiwifruit does impact positively on sleep and recovery in general, and on some but not all of the sleep and recovery doamins highlighted throughout this thesis.

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